Personal Investigation 2 - A Correlational Study Involving A Stroop Test

Question 1

What is the strop test

Answer 1

The Stroop effect (first identified by John Ridley Stroop in 1935) is the delay in reaction time between automatic and controlled processing of information, in which the names of words interfere with the ability to name the colour of ink used to print the words.

Question 2

What previous research suggests Stroop test performance correlates with fitness​

Answer 2

• Predoven et al (2012)
• carried out an experiment on 50 older adults
• found that those who had been randomly assigned to the training programme condition and carried out 3 60-minute physical training sessions a week showed enhanced Stroop performance after 3 months than the control group who did no physical training

Question 3

Describe the methodology

Answer 3

• This correlational study will investigate the relationship between cardiovascular fitness (co-variable 1) and Stroop test performance (co-variable 2).
  -Cardiovascular fitness will be measured by resting heart rate (beats per minute) and Stroop test performance by the time difference (seconds) in the reading of the two word lists (‘congruent’ and ‘incongruent’) in the Stroop test.
• The sample will be 15 participants who will all be A-level Psychology students from the same Sixth Form at the same school in Hampshire, aged between 17 and 18 years of age.
• The sample will be drawn from a target population of all A-level Psychology students at the same sixth form at the same school in Hampshire.

Question 4

Describe the procedure

Answer 4

Question 5

Explain how you operationalised the Stroop test (co-variable 1) in your correlational study

Answer 5

• Participants read the congruent and incongruent word lists on an online Stroop test and their performance for each one was timed in seconds
• The difference between the two times was calculated.

Question 6

Explain the fully operationalised co-variable in your research other than the Stroop test

Answer 6

Each participant’s cardiovascular fitness was measured by taking their radial pulse for 30 seconds and multiplying it by two to achieve a beats per minute value which was their resting heart rate.

Question 7

State the aim of your correlational study

Answer 7

To investigate if there is a relationship between Stroop test performance (the time difference in seconds between performance on a congruent and incongruent list) and cardiovascular fitness measured by taking a radial pulse for 30 seconds and multiplying it by two to get the resting heart rate.

Question 8

Identify whether you chose a directional or non-directional alternative hypothesis.

Answer 8

Directional

Question 9

Explain your choice of hypothesis

Answer 9

I chose a directional hypothesis as previous research by Buck et al suggested that in children, greater aerobic fitness was associated with better performance (a smaller time difference) on the Stroop test.

Question 10

Write an alternative hypothesis for your correlational study

Answer 10

There will be a significant positive relationship between Stroop test performance measured by the time difference (seconds) in reading a congruent and incongruent word list, and cardiovascular fitness measured by taking a radial pulse for 30 seconds and multiplying it by two to get the resting heart rate

Question 11

Write a null hypothesis for your correlational study

Answer 11

There will be no significant relationship between Stroop test performance measured by the time difference (seconds) in reading a congruent and incongruent word list, and cardiovascular fitness measured by taking a radial pulse for 30 seconds and multiplying it by two to get the resting heart rate.

Question 12

Explain one extraneous variable that you considered in your correlational study

Answer 12

The noise levels in the room could be a situational variable. If several participants completed their Stroop tests at the same time, which involves saying words out loud, it could be distracting so they may be more effected by the Stroop effect than than normal.

Question 13

Explain how you managed this variable in your correlational study

Answer 13

So, I asked the participants to wait in silence whilst each participant took a turn each completing the Stroop tests so there was no uncontrolled noise to distract them so their Stroop test performance was related to their cardiovascular fitness and not noise.

Question 14

Explain how one confounding variable could have influenced your correlational study

Answer 14

Some of my participants had a psychology test to do an hour after I did my research with them, so the stress of the test may have increased their resting heart rate or impacted their attention levels which would interfere with the relationship between Stroop performance and cardiovascular fitness.

Question 15

•Explain how you used a correlational study in your research

Answer 15

I used a correlation to analyse the relationship between two continuous variables (co-variables) of Stroop performance and resting heart rate.

Question 16

Strengths of correlational studies

Answer 16

• I was able to establish the direction and strength of the relationship between Stroop performance and resting heart rate, so this can then be used to inspire future experimental research.
• Using correlation was appropriate as it was more practical for me to measure resting hart rate rather than to manipulate cardio vascular fitness as it would’ve taken a long time to make a change to cardio vascular fitness

Question 17

Weaknesses of correlational studies

Answer 17

• My correlation did not show cause and effect between Stroop performance and resting heart rate.
  So l cannot conclude that an increase in Stroop performance was caused by the resting heart rate or vice versa, I could only conclude that a relationship exists.
• My correlations only showed whether a relationship exists not how or why Stroop test performance and resting heart rate are related. There may be other external variables that explains the relationship, like intelligence

Question 18

Outline the location of the research in your correlational study.

Answer 18

My study was a laboratory location because participants were in a classroom which I set up to for doing the Stroop test. I had access to equipment like the use of laptops for the Stroop test and controlled where the laptops were laid out.

Question 19

Outline one strength of conducting research in the laboratory in your correlational study

Answer 19

Using a laboratory meant I had high control over the classroom environment, and therefore potential situational variables such as the lighting conditions, and this increased the internal validity of my results.

Question 20

Outline one weakness of conducting research in the laboratory in your correlational study

Answer 20

My choice of laboratory meant that the students were constantly reminded they were in an experiment because of the controlled environment which may have led to demand characteristics whereby they guess the aim and deliberately take longer on their Stroop test to match their heart rate.

Question 21

Explain two ethical issue which you considered in your correlational study

Answer 21

• One issue could have been confidentiality as I could have recorded the participants names next to their data for their resting heart rate and Stroop test timings making them identifiable.
• One issue could have been risk of humiliation because my participants could be embarrassed about their Stroop test performance if their time was slow and they knew I would be looking at and analysing their data.
• One issue could have been risk of humiliation because my participants could be embarrassed about their resting heart if it was fast as they may think it makes them sound unfit and they knew I would be looking at and analysing their data.

Question 22

Explain how you managed the ethical issues identified previously

Answer 22

• I managed confidentiality by allocating all my participants a number between 1-15 instead of recording their names so they could not be identified from their resting heart rate or Stroop test performance.
• I managed risk of humiliation by telling my participants that they had the right to withdraw in the consent form that they signed. This meant that they could leave my study at any point if they felt embarrassed about their Stroop performance. Additionally at the end I reassured them their Stroop performance time was normal.

Question 23

ldentify the target population in your correlational study.

Answer 23

All A-Level Psychology students at the same sixth form at the same school in Hampshire.

Question 24

ldentify the sampling frame used in your correlational study

Answer 24

Students from one class of U6th psychology students from the Sixth Form of one school in Hampshire.

Question 25

Outline the sampling technique used in your correlational study

Answer 25

used opportunity sampling as l chose students at my convenience because l selected 14 students from the U6th psychology class that happened to have a psychology lesson in the classroom when I was ready to carry out my stroop test. So they were the students available to me at the time.

Question 27

Explain one strength of the sampling technique used in your correlational study.

Answer 27

It was quicker and easier for me to collect participants in comparison to other sampling techniques like self-selected as students were selected at my convenience using the people who were right there at the time I wanted to carry out the Stroop test. I didn't have to generate an advert and wait for people to reply to do my study on Stroop test and resting heart rate, saving me time and costs for resources.​

Question 28

Explain one weakness of the sampling technique used in your correlational study

Answer 28

I ended up with a biased sample, because the selection was students who were my friends in the U6th psychology class, so my sample may share many attributes that might effect their Stroop test score and heart rate. Therefore this is not very diverse and may not be representative of the Stroop performance and heart rate of my target population.

Question 29

Explain how you used primary sources in your correlational study

Answer 29

I collected information on the participants' Stroop test performance and resting heart rate first-hand as I collected this data myself to test my aim without looking at data from other researchers.

Question 30

Outline one strength of using primary sources in your correlational study

Answer 30

I was able to control the format of exactly how my data on Stroop test performance and resting heart rate was collected. I chose the Stroop test from the University of Washington so that it related to the aims of my research, making it valid.

Question 31

Outline one weakness of using primary sources in your correlational study

Answer 31

I was concerned as my use of primary sources meant it was more time consuming than secondary sources as l had to collect and analyse data on heart rate and Stroop test performance myself as it was not readily available. For example, it would be easier to et Stroop data which already existed.

Question 32

Explain one strength of collecting quantitative data in your correlational study.

Answer 32

My quantitative data was easier to analyse using statistics than qualitative data. For example because it is numerical I did not have to interpret and turn the data into quantitative data before using it in an inferential statistical tests so it was quicker and easier to find out if there was a significant relationship between Stroop tests performance and resting heart rate.

Question 33

•Explain one weakness of collecting quantitative data in your correlational study. My data lost the 'human' level of behaviour as I represented their fitness by just a number of BPM for their resting heart rates. This doesn't give them the opportunity to give an in-depth response about their cardiovascular fitness. Or My data offered a very shallow view of cardiovascular fitness because I summarised this with their resting heart rate (bpm) and it will not have the same insight as qualitative data would have which could give a more detailed picture of overall fitness.

Answer 33

- My data lost the 'human' level of behaviour as I represented their fitness by just a number of BPM for their resting heart rates. This doesn't give them the opportunity to give an in-depth response about their cardiovascular fitness. - My data offered a very shallow view of cardiovascular fitness because I summarised this with their resting heart rate (bpm) and it will not have the same insight as qualitative data would have which could give a more detailed picture of overall fitness.

Question 34

Identify the level of measurement in your correlational study

Answer 34

- RHR (BPM) = Ratio - Stroop performance (seconds) = Interval —> because the time in seconds could be negative, because it is a difference between the times for each list if the incongruent word list had been faster then it would have given a negative value.

Question 35

Outline 1 strength of using the mean

Answer 35

- I chose the mean as it meant I could do further statistical analysis by calculating the standard deviation using the Stroop test performance time, and this then allowed me to see the spread of my data around the mean. - I chose the mean as I knew it could always be found when using ordinal or above level data, which I did in my study as l collected ratio data with Stroop test performance time.

Question 36

Outline 1 strength of using the mode

Answer 36

- I chose the mode as it wouldn't generate a 'nonsense' value as the value has definitely occurred in the data set. For Stroop test performance time the mode was ??? as ??? participants scored ?? seconds whereas ???? (the mean) is a nonsense value. - It is not influenced by anomalous results. For example, Participant 11 got a Stroop test performance time of 20 and this deviates from the other participants. The mode will not be artificially inflated by this result as the most common Stroop test performance time is selected instead.

Question 37

Outline 1 strength of using the median

Answer 37

- It is not influenced by anomalous results. For example, Participant 11 got a Stroop test performance time of 20 and this deviates from the other participants. The median will not be artificially inflated by this result as the middle Stroop test performance time value is selected instead. - It can always be found when using ordinal or above level data. I collected ratio data as it was Stroop test performance time but if I used nominal data like how is your cognitive processing speed? (poor/good) then I wouldn't be able to use the median.

Question 38

Outline 1 weakness of the mean

Answer 38

- It was influenced by the anomalous results in my data. Participant 11 got a Stroop test performance time of 20 and this deviates from the other participants. The mean was artificially inflated by this result as all data points are included. - Calculating the mean produced a 'nonsense' value not in the original data set. The mean Stroop test performance time was 13.7 but this is nonsense values as no participant got that time.

Question 39

Outline 1 weakness of the mode

Answer 39

- In my study there was more than one mode - my mode was 4 and 6 and I would prefer one number to summarise my data. - I had a skewed distribution for Stroop test performance time as the mode was 4 but the median was 7 so my mode did not display what is occurring in the centre of the data set.

Question 40

Outline 1 weakness of the median

Answer 40

- It was not useful in my further statistical analysis as I calculated the standard deviation but the median score on the Stroop test performance time wasn't used in that calculation only mean. - Calculating the median produced a 'nonsense' value not in the original data set. The median Stroop test performance time was 7 but this is a nonsense value as no participant got that score.

Question 41

Outline a strength of using the range

Answer 41

- The range for the Stroop test performance time was easier for me to calculate than the standard deviation as I took the lowest score from the highest, so it was less time consuming. - It was appropriate as l collected frequency data as my sample gave me a Stroop test oerformance time and their resting heart rate.

Question 42

Outline a weakness of using the range

Answer 42

- The range was influenced by anomalous results as Participant 11 got a Stroop test performance time of 20 and this deviates from the other participants; this is a problem because only the highest and lowest scores are considered in the calculation. - My range would fail to consider the distribution of scores around the mean for their Stroop test performance time, so I won't know if the times are close to the mean or not.

Question 43

Outline one strength of calculating the standard deviation in your correlational study

Answer 43

When I calculated SD it gave me a more representative measure of dispersion unlike the range, because all of the Stoop test performance times are reflected because every score in the data set is used in the calculation (unlike the range which just uses the top and bottom). It gave me an indication of how close most of the Stoop test performance times were to the mean.

Question 44

Outline one weakness of calculating the standard deviation in your correlational study

Answer 44

It was more time consuming when I calculated the SD compared to the range as I had to use a complicated formula for SD with 6 steps and using all the data but with the range it would be quicker to minus the highest score from the lowest.

Question 45

Explain why calculating a standard deviation is better than calculating the range for your correlational study

Answer 45

When I calculated SD it gave me a more representative measure of dispersion unlike the range, because all of the Stoop test performance times are all reflected every score in the data set (unlike the range).

Question 46

Outline one conclusion that can be drawn from your two standard deviations

Answer 46

There is a larger variation around the mean for Stroop test performance as the SD was 4.3 whereas there was a smaller variation around the mean for resting heart rate as the SD was 3.1.

Question 47

Explain how the data from your correlational study is plotted on a scatter diagram

Answer 47

Stroop test performance time was plotted on the x-axis and resting heart rate was plotted on he y-axis. The data for each of my co-variables were displayed as dots. The position of each dot represents the numerical data for each of my co-variables.

Question 48

Explain why a scatter diagram is the appropriate graphical representation for your data

Answer 48

My scatter diagram was suitable as my data was continuous as I measured Stroop test performance time in seconds and resting heart rate in beats per minute. Each dot represented an individual's two scores for my co-variables.

Question 49

-Outline one conclusion from the scatter diagram you have drawn

Answer 49

There was a positive correlation between Stroop test performance time and resting heart rate. As Stroop test performance time increased, so did the resting heart rate.

Question 50

Draw the scatter diagram

Answer 50

Question 51

Oldentify and fully justify the inferential statistic you use to analyse the data in your correlational study

Answer 51

- Spearman's Rank test. - My data was at least ordinal data as I measured Stroop test performance time which was the time difference between the two lists which was interval and resting heart rate in beats per minute which was ratio. - I was testing for a relationship between the Stroop test performance time and resting heart rate. My data was related as each participant gave two results - one for Stroop test performance time and one for their resting heart rate.

Question 52

Explain whether or not you found a significant result in your correlational study.​

Answer 52

Because the observed value of xxx is greater than the critical value of X.XX the results are significant at a significance level of p< 0.05 for an N of X (X participants) for a one-tailed hypothesis, therefore I rejected my null hypothesis. OR Because the observed value of xxx is not greater than the critical value of X.XX the results are not significant at a significance level of p< 0.05 for an N of X (X participants) for a one-tailed hypothesis, therefore I accepted my null hypothesis.

Question 53

Explain one issue of reliability in your correlational study

Answer 53

One issue of reliability which may have occurred is lack of standardisation of the procedure if some of the participants measured their resting heart rates in different ways and for different time periods this measurement would not be consistent.

Question 54

Explain how you dealt with the issue of reliability identified previously

Answer 54

I dealt with this by explaining to the participants to all measure their pulse at their wrists with their index and forefinger (radial pulse) and showed them how to do it, and asked them to count the beats for 30 seconds using a timer on the board and times their results by two to get a BPM so how they measured their pulse was standardised and consistent for all participants.

Question 55

Explain one issue of validity in your correlational study

Answer 55

If I the used a stop watch to time how long the participants took to read the words in each stoop test list it could lead to researcher bias because I might have started and stopped the stop watch deliberately quicker or slower for each participant based on their heart rate to fit the relationship between cardiovascular fitness and Stroop performance I expected.

Question 56

Explain how you dealt with the issue of validity identified previously

Answer 56

In order to avoid this researcher bias happening I used an online Stroop test that timed how long the participants took to read each list so I did not have to time them myself. The online Stroop test was objective and gives an accurate time for each participant unaffected by my expectations.

Question 57

Suggest two ways in which your correlational study could have been improved

Answer 57

1) I could use a random sampling technique instead of opportunity sampling. I would do this by asking a teacher for a register with all the names of the U6th psychology students and assign them all a number. Then I would use a random numbers generator to select 14 of them. This would reduce researcher bias as I would not be selecting the sample myself, and also improve the representativeness of the sample because everyone in the target population has an equal chance of being selected. 2) I could change the way l operationalised cardio vascular fitness. Rather than use one measure of resting heart rate I would ask my participants to wear a wearable heart rate monitor for a week and then use their average restring heart rate across that week. That would improve the internal validity of my data because it would be a more accurate measure of resting heart rate that isn't affected by any mistakes in counting or by a one off measure at one point in time.